Time of activity of a female free-ranging Lynx (Lynx lynx) with youitg> kittens in Slovenia

11 Pages·1999·7.4 MB·English

by  Stefan Halle

A
Z. Säugetierkunde64(1999) 65-75 ZEITSCHRIFT^gPTUR
© 1999Urban&FischerVerlag SÄUGETIERKUNDE
http://www.urbanfischer.de/journals/saeugetier INTERNATIONALJOURNAL
OF MAMMALIAN BIOLOGY
Time ofactivity ofa female free-ranging Lynx (Lynx lynx) with%youitg>
kittens in Slovenia «:
los f—°
ByIlkaReinhardtandS. Halle \-jo
InstituteofEcology, Ludwig-Maximilians-UniversityMünchen, München
ReceiptofMs. 19^05 1998
.
AcceptanceofMs. 14/1^1998
Abstract
We investigated the activity behaviour and time-budget of a female free-ranging lynx
(Lynx lynx) in Slovenia during the first five months of post-partum from June-October
1995. Activity was monitored by means of a radio-collar with activity sensor, employing
A
continuous automatic recording and discontinuous time-sampling. total of 1818 data
hours was analysed with respect to the prey Status, distinguishing between days with and
without kill, and age of the kittens. On average the female was active for 8.5 h per 24-h
day. Activity at twilight and during daytime was generally higher than during night. On
days when the female hunted she was more active and more diurnal than on days when
she had access to a kill. During the later post-partum mobile phase the female covered a
considerably larger home ränge, was much more active, and showed higher twilight and
daytime activity than during the earlier stationary phase. Movements to and from a kill
occurred irregularly throughout the night during the stationary phase, while the whole fa-
mily went to a kill around sunset and returned back around sunrise during the mobile
phase. When a kill was available, the female spent on average 81 % of the 24-h day with
%
her kittens, but only 63 on days with no kill. Times of absence from the den did not in-
crease during the stationary phase as the kittens grew older. Activity timing is interpreted
as a highly differential temporal adaptation to meet various contrasting challenges, i.e.,
hunting, defence ofkills against competitors, protection ofyoung, and home ränge patrol-
ling. Comparison with data from Switzerland suggest that habitat structure in addition is
likely to shape lynx activity in different areas.
Key words: Eurasian lynx, activity, radiotelemetry, time budget, breeding
Introduction
Recently, the Eurasian lynx (Lynx lynx) appaers to be regaining parts of its former areas
of distribution (see Breitenmoser-Würsten et al. 1998) due to re-introduction and legal
protection. In this connection it is particularly interesting to know to which extent the
species is able to adapt its behaviour to different ecological conditions. Two important as-
pects in this regard are hunting activity and time budgets, since flexible responses to the
environment are to be expected with these behavioural traits in particular. However, data
on lynx activity behaviour are rather fragmentary. In general, the species is assumed to
be primarily nocturnal and crepuscular (Matjuschkin 1978; Hemmer 1993), although
diurnal activity is also known to occur (Haller and Breitenmoser 1986).
0044-3468/99/64/02 - 065 $12.00/0
66 IlkaReinhardtandS.Halle
Even less information is available on the relation between activity and breeding. The
female lynx restricts its movements to a small part of its home ränge during the early
rearing period, as also known from other Felidae (Seidensticker 1977; Sunquist 1981;
Schmidt et al. 1997). Restricted Space use is likely to be reflected in the activity pattern
because the daily time schedule is closely linked to spatial behaviour. However, a feasible
ad-hoc assumption about the total activity level is not possible since a breeding female
has to balance the requirements of food intake with the specific challenges of rearing kit-
tens. Increased hunting effort due to limited use of Space during the early stationary
phase may cause higher activity, while the extended use of Space during the later mobile
phase may also account for this as well.
In general, predators are known to time their activity in accordance to the activity
pattern of their prey (e.g. Ables 1969; Sunquist 1981; Ferguson et al. 1988; Beltran
and Delibes 1994). However, when a lynx manages to kill a large prey like a roe deer,
which is the main prey of the European lynx (Pulliainen 1981; Sostak and Bunevic
1986; Breitenmoser and Haller 1987; Jedrzejewski et al. 1993; Pulliainen et al. 1995),
it may feed on it for up to one week (Reinhardt, pers. obs.). Having a kill or not can be
supposed to affect the activity behaviour directly, with the assumption that the level ofac-
tivity will be lower when the animal has a kill to feed on. Furthermore, also the temporal
pattern of activity over the 24-h day may vary between days with and without kill, be-
cause time can be allocated to different types of activity depending on the short-term
food supply. Almost nothing is known about this aspect oflynx behaviour.
In this study we present data on the activity and time budget of an intensively studied
free-ranging female lynx in Slovenia during the first five post-partum months. In particu-
lar, we focus on the effect of prey Status on temporal behaviour during two distinctive
rearing periods.
Material and methods
Studyarea
The study was conducted in the Kocevska region in Southern Slovenia (45°35'N, 45°20'E). The
620km2 study area is part ofthe Dinara Mountain Range. Elevations ränge from 300 to 1300m. The
fine-scale reliefis typical ofhigh karst regions with numerous dolines, caves, boulder fields, and rock
faces. Forest Covers up to 90% of the terrain with Abieti-Fagetum-dinaricum as the dominant forest
Community. The climate is temperate Continental with annual precipitation from 1400 to 1800mm.
The average meantemperaturesinJanuaryandJuly are-2.9 and 17.8°C,respectively.
Potentiallargerpreyspecies oflynx are reddeer (Cervus elaphus; annual harvestquote of2-3an-
imals/100ha), roe deer {Capreolus capreolus; annual harvest 0.7/100ha), and a few chamois (Rupica-
pra rupicapra). Species that may compete or otherwise interact with lynx include brown bear (Ursus
arctos), wolf{Canis lupus), redfox (Vulpes vulpes), goldenjackal {Canisaureus),wildcat {Felissilves-
tris), badger (Meies meles), wild boar (Sus scrofa; annual harvest 0.8/100ha), and a variety of raptor
species.
Activityreading
The lynx female was caught in a box-trap in April 1994. It was tranquillised with Zoletil 100 (Virbac,
France, a mixture of Tiletamin and Zolazepam), ear-tagged, and fitted with a radio-collar equipped
with a tip switch as activity sensor (Wagener, Germany). The tip switch caused the pulsingrate ofthe
transmitted signal to alter between slow and fast, depending on collar position. In addition, signal
strength varied due to changes in transmitter orientationrelative to the lynx body, and relative to the
receiverantenna. Since we were mainlyinterestedinlocomotoractivity, lynx activitywasindicatedby
changes inbothsignal strengthand/orpulsingrate.
Timeofactivityofafemalelynxwithkittens 67
Activitywasrecordedintwo differentways: Continuousrecordingwasperformedbymeans ofan
automatic recording Station (B+R Ingenieurgesellschaft, Germany), which allowed determination of
lynx activity for each single minute. In addition, discontinuous activity recording (time-sampling) was
used when the lynx was outrunning the receiving area of the recording Station. It was then followed
by car, and radio Signals were monitored every 5th minute for 60sec with a hand-held Yagi-antenna
and aportable receiver. A sample was classified "active" when three ormore signal changes occurred
duringone minute, while inactivitywasindicatedby a steadysignalpulse. In thiswaywe followedthe
"predominant activity sampling procedure" which is considered most accurate for temporal activity
assessment (Tylor 1979). Compatibility ofthe two methods ofactivity readingwas tested by simulta-
neous automaticrecordingandtime-samplingfor20h,whichrevealed ahighagreement of96.7%.To
make both methods directly comparable in data analysis the tapes from continuous recording were
time-sampledto simulate discontinuous activityrecording.
The lynx gave birth to two kittens on the 1 June 1995 and was then followed during the first five
months of rearing, i.e., from June until October 1995. During the first weeks after birth lynx kittens
remain stationary at the den-site to which the female always returned from hunting (called "station-
aryphase" hereafter). Duringthis time the recordingStationwas keptnearto the den-site, fittedwith
a directional antenna orientedtowards the den. This allowedto recordfemale activitynearthe den as
well as times and length of den attendance. When lynx kittens have grown up to an age of seven to
eight weeks, mother and young left the natal area and the kittens started accompany their mother
(called"mobile phase" hereafter).
Dataanalysis
Lynx activity was analysed with respect to the overall level of activity, the activity distribution over
the 24-h day, and the relative activity allocation to different light phases. Twilight was defined as 1h
before and after sunrise and sunset, respectively. The basic time unit was hours ofthe clock. The pro-
portion of samples scored active during each hour yielded the percent activity per hour, with the re-
strictionthatonlyhourswithatleastsixactivitysampleswereregardedinthe analysis.The activityle-
velwasmeasured asthe average activityperhour, perday, orperlightphase.
Relative diurnality and crepuscularityindiceswere employedto compare the activity allocationto
light phases between periods with different levels of activity and with different day length. The di-
urnality index ID (modified after Halle 1995) reflects the proportion ofdiurnal as compared to noc-
turnalactivityandwascalculatedby
= (EAD)/hD •2-1
Id (EAD)/hD+ (EAN)/hN
in which£AD andXAN are the times ofactivity summarisedfor day andnight, respectively, and hD
and hN are day length and night length, respectively. ID is positive if diurnal activity prevails (maxi-
mum: +1 when exclusively diurnal) and negative when nocturnal activityprevails (minimum: -1 when
exclusively nocturnal). The crepuscularity index Ic (modified afterHalle 1995) reflected the relative
proportionoftwilightactivityascomparedtotheaverageactivityoverthe24-hdayandwasvaluedby
where IAC is the time of activity during the hours oftwilight (SR±1h and SS ± 1h) and IA is the
totaltime ofactivityduringanentire day. Icispositivewhen activityduringtwilightisincreasedcom-
paredtothe average activity, andnegativewhenitis decreased.
Lynxactivitybehaviourwasanalysedforthe totalstudyperiod,the tworearingperiods, andinre-
lation to the prey Status. For the latter all days ofthe field season (separated by midnight) were cate-
gorisedaccordingtopreyStatusbylocatingthe female severaltimes a dayusingthe methods oftrian-
gulation (or "homing in", White and Garrot 1990). Locations where the lynx remained for an
evening or night were searched for carcasses ofprey killed by lynx the following day with a trained
dog. Days were classified as "day with kill" if the kill was actually found, or if the lynx returned to
the same place for several nights. Ifthere was no indication of a kill, i.e., when the lynx changed its
Position considerably in successive nights, the Status "day without kill" was given. When data where
ambiguous, days were classified as "status unknown". Note that this Classification, however, only ap-
68 IlkaReinhardtandS.Halle
plies to large ungulate prey and not to voles andothersmall prey items, whichmaybe foodresources
aswell (e.g. Pulliainen 1981;Jedrzejewski et al. 1993; Pulliainenet al. 1995).
Differences in activity distribution over the 24-h day were tested with the Kolmogorov-Smirnov-
test. When testingfor differences depending on prey Status, datafrom days withunknown Statuswere
excluded. Wilcoxon-signed-rank-tests for related samples were used for comparisons between days
with andwithout kill, andbetweenthe tworearingperiods. Inthe samewaywe testedwhetherthefe-
male was more often absent from the den during the second halfofthe stationary phase than during
the first. We used Kruskal-Wallis one-way analysis ofvariance forindependent samples, adjusted by a
Bonferroni procedure (c.f. Toutenbourg 1994), to test for differences among the average activity le-
vel at daytime, night-time, andtwilight. AllP-values are fortwo-tailedtest.
Results
GeneralactivitypatternandpreyStatus
The total base of activity data consisted of 1818 data hours of which 1275 h (70%) were
covered by automatic recording and 543 h (30%) by time-sampling. Each hour of the
clock (1:00-24:00) was represented by 59 to 95 data hours with an average of 11.1 activity
samples per hour. For 1490h from 103 days the prey Status was known, of which 824h
from 49days were classified as "days with kill" and 666h from 54days as "days without
kill".
On average, the lynx was active for 35.5 % (N= 1818, SD = 32.18, SE = 0.75) or 8.5 h
of the 24-h day. Averaged over the entire study period the daily activity pattern revealed
no significant deviation from an even distribution over the 24-h day (N= 1818, Kolmo-
gorov-Smirnov, z = 12.29, P<0.001). However, after Splitting days into three distinct light
phases, the overall level of activity differed significantly among them (N = 1818, Kruskal-
Wallis, df=2, P = 0.001), being highest during twilight, intermediate during daytime, and
lowest during the night.
The lynx was more active on "days without kill" (45.7%) than on „days with kill"
(28.3%; N=24, Wilcoxon, P<0.001). Twilight and diurnal activity always prevailed but
particularly so on "days without kill" (Ic = +0.12, ID = +0.15 as compared to Ic= +0.03,
ID - +0.06 on "days with kill"). This indicates predominant hunting during broad day
light.
Rearingperiods
During the stationary phase the lynx used only 8km2 of her home ränge as compared to
110km2 during the later mobile phase. Correspondingly, the female was significantly
more active during the mobile phase (39%) than during the stationary phase (29.7%;
N = 24, Wilcoxon, P= 0.004). This activity increase was above all caused by much higher
day and twilight activity, whereas nocturnal activity decreased during the mobile phase,
resulting in a substantial change in the daily activity pattern (Fig. 1). Activity distribution
over the three light phases was fairly even during the stationary phase (N= 683, Kruskal-
Wallis, P = 0.241), while the difference twilight>day>night was highly significant during
the mobile phase (N = 1135, Kruskal-Wallis, P<0.001; twilight vs. daytime: N= 706,
P<0.001; daytime vs. night: N = 964, P<0.001). Accordingly, diurnality and crepuscular-
ity indices were higher for the mobile phase (ID = +0.13, Ic= +0.13) than for the station-
ary phase (ID =-0.04, Ic=-0.06).
For the effect of prey Status on activity behaviour (Fig. 2), only "days with kill" could
be compared between the two rearing periods, because too few data from "days without
kill" were available for the stationary phase. On "days with kill" the activity level was
%
about 28.6 during the stationary phase with an almost even distribution over all light
Timeofactivityofafemalelynxwithkittens 69
25
Fig.1. Diel distribution ofoccasions when the lynxwas recorded to move more than 500m per hour.
Solidline: stationaryphase, brokenline: mobile phase. The bars atthe top indicate twilight andnight-
timehours.
with kill without kill
80
^ 60
stationary £ 40
I
phase * 20
o
day twilight night
phase
Iight
60 «j 60
o
mobile 40 cd 40
phase 20 ^ 20 1_
0
day twilight night day twilight night
Iight phase Iight phase
Fig.2. Meanvalues (±SE) ofactivityforeachlightphase (daytime, twilight,night-time), measured as
the percentage ofan hourwith activity. Data are broken down to the two rearing periods and to the
effectofpreyStatus.Forthe stationaryphasetoofewdatawere availablefor"dayswithoutkill"toin-
cludethiscategoryintheanalysis.
conditions (N =344, Kruskal-Wallis, P=0.188; ID =-0.09 and Ic= +0.04). The level of ac-
tivity was almost the same during the mobile phase on "days with kill" (28.1 %), but now
activity differed significantly among light phases (N =480, Kruskal-Wallis, P<0.001), de-
creasing in the order twilight>day>night (daytime vs. twilight: N=407, P<0.001; night
vs. daytime: N=257, p=0.003; ID = +0.13, Ic= +0.19). Crepuscular activity was by then
about 1.6times higher than the 24-h average.
70 IlkaReinhardtandS.Halle
stationary phase
10
8
na> 6
E
=5 4
H
n f nn F IJJL
0 2 4 6 8 10 12 14 16 18 20 22 24
t i m e of d ay
mobile phase
0 2 4 6 8 10 12 14 16 18 20 22 24
t i m e of d ay
Fig.3. Diel distribution ofmovements between the daytime location and the kill during the two rear-
ingperiods.Blackbars:movingtothekill,shadedbars:returningfromthekill.Thebarsatthetopindi-
catetwilightandnight-timehours.
The reason for this difference in behavioural parameters became obvious when look-
ing at the times when the lynx went to or returned from the kill (Fig. 3). As long as the
kittens were stationary the female went to the kill and returned to the den at variable
times. Later, when the kittens followed their mother, the pattern became much more reg-
ulär, i.e., the family went to the kill in the evening and early night, and returned back to
their resting place in the late night and early morning. During the mobile phase the level
of female activity almost doubled on "days without kill" (51.5%) as compared to "days
with kill" (28.1 %). When she had no kill and was hunting, significantly more activity was
performed during daytime and twilight than during the night (daytime vs. night: N=383,
P<0.001; twilight vs. night: N=265, P<0.001; Fig. 4, c.f. Fig. 2).
To determine whether the female had preferred times for sleeping we computed the
averages of the longest inactive period per hour of the day. The resultant 24-h pattern
Timeofactivityofafemalelynxwithkittens 71
mobile phase
t i m e of d ay
Fig.4. Patternoffemaleactivityat"dayswithkill" (black)and"dayswithoutkill" (shaded)duringthe
mobilephase.Thebarsatthetopindicatetwilightandnight-timehours.
was compared with the total distribution of inactivity (60min.-Xmin. active/h) for the
two rearing periods as well as for days with and without kill. The distributions always cor-
responded well with each other (N = 24, Spearman rank correlation, all P<0.001, station-
ary phase: rs =0.72; mobile phase: rs= 0.92; "days with kill": rs =0.81; "days without
kill": rs =0.86), indicating that sleep was an integrated part of the main rhythm of activ-
ity and inactivity, respectively.
Denattendance
From 1 June the animal returned constantly to the same small area where she had her
breeding den the previous year (Huber, unpubl. data). After a disturbance on 23June the
female moved to a second den, approximately 400m up the slope, where two kittens
aged about 4weeks were found on 2July. Also later during the stationary phase the lynx
family repeatedly changed location a few hundred metres, so obviously the female had ac-
cess to several auxilliary dens that where used alternatively. The female always returned
to the place where she started from, so she probably was not accompanied by her kittens
during the excursions. On 19July the lynxes moved 3.5 km (straight line) to a place well
outside the area where the female has been hunting during the previous seven weeks.
During the stationary phase the female spent on average 17.9h of the day (74.5%)
near her kittens at the den. The time of presence, however, differed significantly between
"days with kill" (80.6%) and "days without kill" (62.6%), being on average 4.5 h longer
on "days with kill" (N =24, Wilcoxon, P<0.001). Relatively, presence at the den-site oc-
curred more often during daytime on "days with kill" than on "days without kill"
(N =400, Mann-Whitney-U, P<0.001, Fig. 5). However, differences in den attendance
during night and twilight hours between "days with kill" and "days without kill" were not
statistically significant (Mann-Whitney-U, night: N = 120, P=0.44; twilight: N= 180,
P=0.27).
On "days with kill" the times of absence from the den corresponded generally well
with the activity records (N=24, Spearman rank correlation, rs= 0.71, P<0.001). How-
ever, activity during daytime was not closely related to the pattern of absence from the
den, indicating high activity in the close vicinity of the den, probably performed as play
72 IlkaReinhardtandS.Halle
den attendance
o
-I 1 , 1 , 1 , , , 1 1 ,
0 2 4 6 8 10 12 14 16 18 20 22 24
time of day
Fig.5. Dieldistribution ofden attendance bythe female at "dayswithkill" (black) and "dayswithout
kill"(shaded)duringthestationaryphase.Thebarsatthetopindicatetwilightandnight-timehours.
and comfort behaviour. The time of absence from the den did not increase as the kittens
grew older, instead it decreased slightly from 28% to 24% of the day (N =24, Wilcoxon,
P= 0.24).
Discussion
We are well aware that the data presented here are restricted to only one individual,
hence the important aspect ofbehavioural Variation among individuals had to be ignored.
However, since there is only scarce information about the activity and early maternal
phase of free-ranging Eurasian lynx, we feel that our approach to focus on one breeding
female and to follow her closely through a whole summer may bejustified.
According to the lumped data from the entire study period, activity appeared initially
to be acyclic. However, a more detailed scrutiny of the data revealed a highly differen-
tiated activity behaviour, in which prey Status and rearing period had substantial effects
on the pattern. In fact, our analysis verified that the flexible pattern of the females activ-
ity allowed for short-term adaptive responses to her and her kittens requirements.
The highest activity of the female was recorded during twilight and daytime, which is
in accordance with a short survey of re-introduced lynxes in Austria (Festetics 1981). In
contrast, Matjuschkin (1978) observed the lynx in Russia to be mostly or predominantly
%
nocturnal with only little diurnal activity. The general activity level of about 36 in our
study was considerably lower than the 58% Aldama et al. (1991) reported for the Iber-
ian lynx (L. pardinus). In particular, the lynx was less active on "days with kill" than on
"days without kill", so obviously a lynx that already has a kill can lower its hunting effort
and, as a rule, does not move over greater distances.
Behaviourduringthestationaryphase
The level of activity was almost the same on "days with kill" during the two rearing peri-
ods, portraying the basic activity level of a female lynx with cubs. During the stationary
phase the lynx fed mostly at night, and also movements between den-site and kill oc-
curred predominantly at night. This resulted in higher nocturnal activity on "days with
kill" as compared to the mobile phase.
Timeofactivityofafemalelynxwithkittens 73
Time of absence from the den-site per day did not gradually increase with age of the
kittens. This contradicts the assumption that the restricted hunting area during the sta-
tionary phase will demand increasing hunting efforts as kittens grow older and need
more food, which in turn would lead to shorter den attendance and higher activity. So
probably, the area close to the den-sites was a hunting ground sufficient to cover food
demands during the entire stationary phase. This assumption is reasonable, since the
large fields of dolines offer rieh grazing for roe deer, while a stalking predator benefits
from good cover.
This estimate of habitat quality, however, raises the question why behaviour at all
A
changes during the transition to the mobile phase, if not for limited food supply. suit-
able explanation may be a need for home ränge patrolling. Home ränge occupation was
reported by Sunquist (1981) for a tigress while the activity ofthe former resident female
was restricted to a small area during the early rearing period. The same resulted for lynx
in Switzerland Breitenmoser et al., 1993). Hence, staying with the kittens too long may
result in a loss of the home ränge, while starting to move with the kittens too early may
endanger the kittens life. An Observation made one week before the female moved with
her kittens a longer distance for the first time may point to this difficult trade-off. The
lynx made a remarkably extensive excursion over 15h to the northern end of her ränge,
and almost the same way was then taken aecompanied by the kittens when they left the
natal area. Thus, the mother most probably pre-explored the travelling route before.
Another reason for giving up the stationary phase may be due to energy constraints.
The energy costs of lactation are high and exceed all other reproduetive costs in euthe-
rian mammals (Loudon 1985). Deag et al. (1987) proved that nursing cats (Felis domesti-
ca) lost weight at an increasing rate over the first eight weeks after parturition. Increasing
costs of lactation may, therefore, demand to provide the kittens with solid food. To our
knowledge there is no report of lynx carrying large prey or parts of it back to the den,
and felids are not able to regurgitate food to their offspring as known from canids. In-
stead, they lead their young to the kill, resulting in the vagabond behaviour ofthe mobile
phase.
Behaviourduringthemobilephase
Activity behaviour during the mobile phase was bimodal (Aschoff 1957), and daytime
was the preferred activity period irrespective of prey Status. When the female had a kill,
she went there together with her kittens in the evening, spent the whole night close to the
kill, and left in the morning. Accordingly, the highest locomotor activity was recorded
during twilight in this Situation. This pattern may reflect a temporal adaptation to protect
the kill against potential seavengers. Jedrzewski et al. (1993) found eight species of sca-
vengers feeding on lynx kills in Poland, with wild boar having the greatest impact. In our
study area the brown bear is probably an important competitor, which is mainly noctur-
nal (Kaczensky pers. comm.). It may be advantageous to stay near the kill at night to se-
cure that the pay-back from time and energy investment is not taken away by another
species. Against visually orientated diurnal seavengers like raptors blinding with leaves
and branches was an efficient technique.
Even on "days with kill" activity was higher during daytime than during the night,
suggesting that play and comfort behaviour mainly occurred during daytime. The activity
rhythm of the kittens may thus partly explain diurnal activity of the female. Many mam-
malian species exhibit diurnal behaviour as juveniles and shift to nocturnality as adults,
which is, for instance, known for Iberian lynx (Beltran and Delibes 1994), wild boar
(Briederman 1971), and badger (Eibl-Eibelsfeldt 1954, cited in Aschoff 1957). If kit-
ten activity would be a decisive factor, increased diurnality should exclusively be shown
by females with young offspring.
74 IlkaReinhardtandS. Halle
After having consumed a kill completely, the female normally moved with her kittens
during broad daylight to another area before hunting. Hunting times of the lynx were
very variable during the mobile phase, but as a general rule tended to be higher during
twilight and daytime. In the Swiss Jura Mountains, however, nocturnal and twilight activ-
ity prevailed distinctively (Bernhart pers. comm.). The different temporal hunting pat-
terns in Slovenia and Switzerland may reflect adaptations to hunting on roe deer, the
main prey oflynx in both areas (Breitenmoser et al. 1993; Huber unpubl. data) in differ-
ently structured habitats. In Slovenia, forest Covers more than 90% of the study area, so
that deer can stay under cover for long periods of time. In this Situation temporally flex-
ible roaming may give the best hunting success. In the Swiss study area, however, forest
%
cover is only about 39 (Bernhart pers. comm.) and roe deer emerge predominantly in
the evening to browse on pastures. Accordingly, lynx hunt especially along the forest
edges during the evening and night (Breitenmoser and Haller 1987) with frequent indi-
cations of ambushing (Kaczensky pers. comm.). Since founders of both populations stem
from the same population of origin in Slovakia (Haller and Breitenmoser 1986; Cop
and Frkovic 1998), behavioural differences between Swiss and Slovenian lynx are likely
to reflect responses to the two areas rather than individual or genetic variance. This indi-
cates that behavioural flexibility of Eurasian lynx allows to adapt foraging to different
ecological situations.
Acknowledgements
We gratefully thank P. Kaczensky andT. Huber for support and critical discussion, andJ. Dieberger
fromthe InstitutfürWildbiologie undJagdwirtschaft atVienna aswell asJ. Stanisafortechnical sup-
port. We alsowanttothank R. MüllerandD. Wirz for assistancewith data analysis andK. Hinden-
lang and two anonymous referees for their constructive comments. Funding was provided by the
AustrianFederal MinistryofScience and Research (G.Z.30.435/-23/92).
Zusammenfassung
AktivitäteinesLuchsweibchens(Lynxlynx) währendderJungenaufzuchtinSlowenien
Aktivitätsverhalten und Zeitbudget eines LuchsWeibchens (Lynx lynx L.) in Slowenien wurden wäh-
rend der ersten fünf Monate der Jungenaufzucht von Juni-Oktober 1995 mittels Radiotelemetrie un-
tersucht. Die Aktivität wurde teils kontinuierlich mit einer automatischen Registrierstation, teils dis-
kontinuierlich durch "time-sampling,, aufgenommen. Insgesamt wurden 1818Datenstunden hinsicht-
lich des Alters der Jungen analysiert, wobei zwischen Tagen mit und ohne Riß unterschieden wurde.
Im Durchschnitt war die Luchsin pro 24Std.-Tag für 8,5Std. aktiv, wobei die meiste Aktivität in der
Dämmerungundtagsübererfolgte. AnTagen ohne Riß warsie stärkerdiurnalundinsgesamt deutlich
aktiver als anTagen mit Riß. Verglichenzurfrühen, stationären Phase derJungenaufzucht, in der die
Luchsin die Jagdausflüge auf einen kleinen Teil ihres Streifgebietes beschränkte, war sowohl die Ge-
samtaktivität als auch die Dämmerungs- undTagaktivitätin der späteren, mobilen Phase höher. Orts-
wechsel zwischen Riß und Tagesstandort erfolgten in der stationären Phase unregelmäßig über die
Nacht verteilt, während Ortswechsel in der mobilen Phase sehr regelmäßig in der Morgen- bzw.
Abenddämmerung stattfanden. An Tagen mit Riß verbrachte die Luchsin durchschnittlich 81% des
TagesbeiihrenJungen,jedochnur63% anTagenohne Riß. Die Zeit derAbwesenheitvonderWurf-
höhle nahm während der stationären Phase nicht mit dem Alter der Jungen zu. Die Verhaltensände-
rungen während der Jungenaufzucht können vor dem Hintergrund gegensätzlicher Erfordernisse
(Jagd. Rißverteidigung gegen Konkurrenten, Schutz der Jungen, Streifgebietskontrolle) interpretiert
werden. Ein Vergleich der Ergebnisse mit Studien aus Gebieten unterschiedlicher Habitat-
struktur läßt darauf schließen, daß das flexible Jagd- und Aktivitätsverhalten des europäischen
Luchses eine Anpassunganverschiedenartige ökologische Bedingungen erlaubt.